<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
</head>
<body>

  <button onclick="loadPhones()" id="button">Load phones.json!</button>

  <script>
    function loadPhones() {

      let xhr = new XMLHttpRequest();

      xhr.open('GET', 'phones.json');


      xhr.send();


      xhr.onreadystatechange = function() {
        if (xhr.readyState != 4) return;

        button.innerHTML = 'Complete!';

        if (xhr.status != 200) {
          // handle error
          alert(xhr.status + ': ' + xhr.statusText);
        } else {
          // show result
          alert(xhr.responseText);
        }

      }

      button.innerHTML = 'Loading...';
      button.disabled = true;
    }
  </script>

</body>
</html>
